I don't do 'digital previews' of my film shots because of the different
photographing experience. Since I shoot film with a rangefinder the
handling is just way different to my digital SLR and I think I shoot a
different style with each camera.
On the other hand I would not use the rangefinder in the studio.

Many photogs with medium formar cams use Polaroid backs to check
the lighting right away - kinda similar to your idea.

it's a matter of preference, really. and in this case, preference usually
means what one has been taught or has become accustomed.

for me it very simply comes down to photography: knowing light. to learn the principles of light (eg - inverse square law of light) is all that you really need to know. if you can work with light, then what's left? what you see through the viewfinder. with lighting 'under your belt', all that is left is to look through the camera and be concerned only with composition.

what does this do for you? well, allow me...

studio example: if i know that i want a pure white background, then it needs to read at least 4 stops above the metered face exposure. if it reads 3 stops above, then i know that by moving the background lights closer by half the current distance doubles the amount of light, i can adjust. over time, you will know exactly where to put light and will not need to preview. with landscapes, well, you either wait out the situation or move your butt and gear or come back another day.

when i first got my film camera .. i kept looking at the back to check for the image ... now i dont even look at the back of my digital camera anymore, i was just thinking today i will turn the preview display off my ditial to save on the batteries (sucks the blood out of batteries)

film forces me to pay attention without getting a preview .. thats a good thing for me.. i got a little lazy there for a minute